U.S. patent number 6,508,226 [Application Number 09/682,575] was granted by the patent office on 2003-01-21 for combustion chamber for direct injection engine.
This patent grant is currently assigned to Yamaha Hatsudoki Kabushiki Kaisha. Invention is credited to Shinichi Kurosawa, Daijirou Tanaka.
United States Patent |
6,508,226 |
Tanaka , et al. |
January 21, 2003 |
Combustion chamber for direct injection engine
Abstract
An improved combustion chamber configuration for a direct
injected internal combustion engine. The cylinder head recess and
piston head are configured so as to provide a small clearance
volume and accordingly high compression ratios while the shape of
the piston head and the arrangement of the cylinder head recess
permits a portion of the injected fuel to be directed toward the
exhaust valves to cool them and reduce smoke and increase fuel
efficiency.
Inventors: |
Tanaka; Daijirou (Iwata,
JP), Kurosawa; Shinichi (Iwata, JP) |
Assignee: |
Yamaha Hatsudoki Kabushiki
Kaisha (Iwata, JP)
|
Family
ID: |
18799321 |
Appl.
No.: |
09/682,575 |
Filed: |
September 21, 2001 |
Foreign Application Priority Data
|
|
|
|
|
Oct 20, 2000 [JP] |
|
|
2000-321141 |
|
Current U.S.
Class: |
123/295; 123/298;
123/305 |
Current CPC
Class: |
F02F
3/26 (20130101); F02F 1/4214 (20130101); F02B
23/104 (20130101); Y02T 10/125 (20130101); F05C
2201/021 (20130101); Y02T 10/123 (20130101); F02B
2075/125 (20130101); F02F 2001/245 (20130101); Y02T
10/12 (20130101) |
Current International
Class: |
F02B
23/10 (20060101); F02F 3/26 (20060101); F02F
1/42 (20060101); F02B 75/12 (20060101); F02B
75/00 (20060101); F02F 1/24 (20060101); F02B
017/00 () |
Field of
Search: |
;123/295,298,305,279 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
6-81651 |
|
Mar 1994 |
|
JP |
|
11-324680 |
|
Nov 1999 |
|
JP |
|
Primary Examiner: Mohanty; Bibhu
Attorney, Agent or Firm: Beutler; Ernest A.
Claims
What is claimed is:
1. An internal combustion engine combustion chamber defined by a
cylinder bore closed at one end by a cylinder head combustion
chamber surface and at the other end by a piston reciprocating in
said cylinder bore, said cylinder head combustion chamber surface
having a pair of angularly related surface portions formed on
diametrically opposite sides thereof, at least one intake port
formed in one of said cylinder head combustion chamber angularly
related surface portions, at least one exhaust port formed in the
other of said cylinder head combustion chamber angularly related
surface portions, said piston having a head portion with an upper
combustion chamber surface, said piston head portion including an
inclined planar surface facing said one cylinder head combustion
chamber angularly related surface portions and inclined toward said
other of said cylinder head combustion chamber angularly related
surface portions, and a fuel injector mounted in said engine on the
side of said combustion chamber formed by said one of said cylinder
head combustion chamber angularly related surface portions and
spraying toward said piston head portion inclined planar surface,
said piston head portion inclined planar surface being offset from
the cylinder bore axis toward said fuel injector such that at least
a part of the fuel injected therefrom will be directed toward said
exhaust port.
2. An internal combustion engine combustion chamber as set forth in
claim 1 wherein there are a plurality of intake ports formed in the
one of the cylinder head combustion chamber angularly related
surface portion, said intake ports being valved by poppet valves
and said piston head inclined surface being formed with recesses
formed to provide clearances for at least two of said poppet
valves.
3. An internal combustion engine combustion chamber as set forth in
claim 1 wherein a second planar inclined surface facing the other
cylinder head combustion chamber angularly related surface portions
is formed on the piston head diametrically opposite the first
mentioned piston head inclined surface.
4. An internal combustion engine combustion chamber as set forth in
claim 3 wherein the piston head inclined surfaces converge toward
the cylinder bore axis where they are joined by a generally flat
piston head surface.
5. An internal combustion engine combustion chamber as set forth in
claim 4 wherein the generally flat piston head surface is displaced
from the axis of the cylinder bore toward the exhaust port so the
first piston head inclined surface lies closer to said cylinder
bore axis than the second piston head inclined surface.
6. An internal combustion engine combustion chamber as set forth in
claim 5 wherein there are a plurality of intake ports formed in the
one of the cylinder head combustion chamber angularly related
surface portion, said piston head inclined surface being formed
with recesses formed to provide clearances for at least two of said
poppet valves.
7. An internal combustion engine combustion chamber as set forth in
claim 6 wherein the piston head inclined surface recesses comprise
a pair of circular portions joined by a straight, tangential wall,
said straight, tangential wall lying parallel to and spaced away
from the axis of the cylinder bore.
8. An internal combustion engine combustion chamber as set forth in
claim 7 wherein a squish area surrounds the one cylinder head
combustion chamber angularly related surface portion recesses.
9. An internal combustion engine combustion chamber as set forth in
claim 8 wherein a groove is formed in the squish area to clear the
fuel injector.
10. An internal combustion engine combustion chamber as set forth
in claim 9 wherein a fan shaped recess extends through the squish
area from the groove for directing the fuel injected by the fuel
injector at least in part on the piston head inclined surface.
11. An internal combustion engine combustion chamber defined by a
cylinder bore closed at one end by a cylinder head combustion
chamber surface and at the other end by a piston reciprocating in
said cylinder bore, said cylinder head combustion chamber surface
having a pair of angularly related surface portions formed on
diametrically opposite sides thereof, a plurality of intake ports
formed in one of said cylinder head combustion chamber angularly
related surface portions, said intake ports being valved by poppet
valves, at least one exhaust port formed in the other of said
cylinder head combustion chamber angularly related surface
portions, said piston having a head portion with an upper
combustion chamber surface, said piston head portion including an
inclined surface facing said one cylinder head combustion chamber
angularly related surface portions and inclined toward said other
of said cylinder head combustion chamber angularly related surface
portions, a fuel injector mounted in said engine on the side of
said combustion chamber formed by said one of said cylinder head
combustion chamber angularly related surface portions and spraying
toward said piston head portion inclined surface such that at least
a part of the fuel injected therefrom will be directed toward said
exhaust port, said piston head inclined surface being formed with
recesses formed to provide clearances for at least two of said
poppet valves, said piston head inclined surface recesses
comprising a pair of circular portions joined by a straight,
tangential wall, said straight, tangential wall lying parallel to
and spaced away from the axis of the cylinder bore.
12. An internal combustion engine combustion chamber as set forth
in claim 11 wherein a squish area surrounds the piston head
inclined surface recesses.
13. An internal combustion engine combustion chamber as set forth
in claim 12 wherein a groove is formed in the squish area to clear
the fuel injector.
14. An internal combustion engine combustion chamber as set forth
in claim 13 wherein a fan shaped recess extends through the squish
area from the groove for directing the fuel injected by the fuel
injector at least in part on the piston head inclined surface.
Description
BACKGROUND OF INVENTION
This invention relates to an internal combustion engine and
particularly one of the type having direct cylinder injection and
more particularly to a combustion chamber for such an engine.
In the interest of improving engine performance in the field of
power, fuel consumption and exhaust emission control, it has been
proposed to employ direct cylinder injection. By injecting fuel
directly into the combustion chamber, it is not necessary to
achieve a homogeneous mixture in the combustion chamber under all
running conditions so as to insure combustion. In other words, if
direct cylinder injection is possible, stratification can be
obtained.
One problem in connection with obtaining a stratified charge and
good combustion under low speeds and low loads is the difficulty in
insuring that a stoichiometric mixture is present at the spark plug
at the time of ignition. Various combustion chamber arrangements
have been proposed with an effort to achieve this. Many of theses
combustion chamber designs employ a bowl that is formed in the head
of the piston and which is configured so as to enable
stratification at least under some running conditions.
For example, FIG. 1 is a prior art cross sectional view taken
through the cylinder of one type of engine that has been proposed
to achieve this goal. This is a combustion chamber of the type that
is disclosed in Japanese Published Application Hei 6-81651,
published Mar. 22, 1994In this engine, there is a combustion
chamber S which is formed by a cylinder bore 11 of a cylinder block
12, a lower surface 13 of a cylinder head 14 which, in that
construction, is detachably connected to the cylinder bloc k 12 and
a piston 15 that reciprocates in the cylinder bore 14. In this
combustion chamber S, the piston has its head portion formed with a
pair of angularly inclined upper surfaces 16 and 17 which face
diametrically opposed portions of the cylinder head lower surface
13 and in which respective intake 18 and exhaust passages 19 are
formed. Intake and exhaust valves 21 and 22 cooperate with the
valve seats formed at the ports of these intake and exhaust
passages 18 and 19 to control the flow of air into the combustion
chamber and exhaust gases out of the combustion chamber.
The piston head inclined portion 16 is formed with a bowl like
recess 23, which is formed primarily on the intake side of the
piston head but extends slightly over toward the exhaust side.
A spark plug 24 is mounted in the cylinder head 14 generally on the
center of the combustion chamber S and the axis of the cylinder
bore 11.
A fuel injector 25 is mounted on the intake side of the cylinder
head 14 and sprays its fuel in a pattern as shown in this figure so
as to impinge upon the cylinder head recess 23. The intake port or
ports 18 are configured so as to cooperate with the bowl 23 to
generate a tumble action as shown by the arrow "a" in this figure.
The theory is that this will cause the fuel deposited in the piston
head bowl 23 to be swept toward the spark plug 24 to insure
stratification under low speed and low load conditions.
There are several disadvantages with this type of combustion
chamber. Because of the fact that the fuel is injected on the
surface of the piston head bowl 23 it tends to become excessively
rich and results in lack of complete fuel evaporation into the
combustion chamber S. This is because more fuel is deposited than
can effectively vaporize and is liable to cause smoke generation
and unwanted exhaust gas emissions.
Another solution to the problem of combustion chamber configuration
and for direct injected engines is shown in Japanese Published
Application Hei 11-324680, and its issued United States Letters
Patent counterpart 6,062,195, issued May 16, 2000. This type of
arrangement is shown in FIG. 2 and again has a combustion chamber S
that is formed by a piston 31 that reciprocates in a cylinder bore
32 of a cylinder block 33. This cooperates with a combustion
chamber recess formed in a cylinder head 34 that is affixed to the
cylinder block 33 in a suitable manner.
Intake passages 35 open into the combustion chamber S and are
valved by intake valves 36 positioned on one side of the cylinder
head. On the other side of the cylinder head, exhaust passages 37
are formed which are valved by exhaust valves 38.
A fuel injector 39 is mounted between the intake valves 36 and
below them and injects fuel into the combustion chamber S which is
formed by the head of the piston 31, which has a slight concave
configuration 41 although it is substantially flat. The fuel
injector 39 sprays its fuel across this slightly concave surface 41
and propagates towards the exhaust valve 38 so as to be heated and
improve fuel vaporization.
In this arrangement, there is a fairly large angle .alpha. between
the stems of the intake and exhaust valves 36 and 38 so that the
exhaust valve will be inclined to receive the fuel and also so as
to preclude the fuel from passing out of the exhaust valve. Thus,
this configuration causes a fairly large volume for the combustion
chamber S at top dead center and makes it difficult to raise the
compression ratio.
It is, therefore, a principal object to this invention to provide
an improved combustion chamber configuration for a direct injected
internal combustion engine.
It is a further object to this invention to provide an improved
combustion chamber configuration permits the attainment of high
compression ratios and avoids the likelihood of fuel condensing in
the combustion chamber recess of the piston and not being able to
evaporate fully before the spark plug is fired. Thus, the
likelihood of smoke in the exhaust and unwanted hydrocarbons can be
substantially reduced.
SUMMARY OF INVENTION
This invention is adapted to be embodied in an internal combustion
chamber. The combustion chamber is defined by a cylinder bore
closed at one end by a cylinder head combustion chamber surface and
at the other end by a piston reciprocating in the cylinder bore.
The cylinder head combustion chamber surface has a pair of angular
related surface portions formed on diametrically opposed sides
thereof. At least one intake port is formed in one of the cylinder
head combustion chamber angularly related surface portions. At
least one exhaust port is formed in the other of the cylinder head
combustion chamber angularly related surface portions. The piston
has a head portion with an upper combustion chamber surface. The
piston head portion includes an inclined surface facing the one of
the cylinder head combustion chamber surface portions and which is
inclined toward the other of the cylinder head combustion chamber
angularly related surface portions. A fuel injector is mounted in
the engine on the side of the combustion chamber formed by the one
of the cylinder head combustion chamber angularly related surface
portions and sprays toward the piston head portion inclined surface
such that at least a part of the fuel injected therefrom will be
directed toward the exhaust port.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a cross sectional view taken through the combustion
chamber of one cylinder of an engine constructed in accordance with
a first form of prior art construction.
FIG.2 is a cross sectional view, in part similar to FIG. 1, and
shows another prior art combustion chamber configuration.
FIG. 3 is a more detailed cross sectional view, in part similar to
FIGS. 1 and 2, but showing the construction associated with one
cylinder of the instant invention.
FIG. 4 is a top plan view of the piston head.
FIG. 5 is a cross sectional view taken along the line 5--5 of FIG.
4.
DETAILED DESCRIPTION
Referring now in detail to the drawings and particularly FIGS. 3
through 5, but initially primarily to FIG. 3, an internal
combustion engine constructed in accordance with an embodiment of
the invention is identified generally by the reference numeral 51.
The entire engine 51 is not depicted because the invention deals,
as afore described, with the combustion chamber thereof, indicated
by the reference character S. Also, only a single cylinder of the
engine is depicted because it is believed readily apparent to those
skilled in the art how the invention can be practiced with engines
having any desired number of cylinders and any cylinder
configuration such as in line, V-type or opposed.
The engine 51 has a cylinder block 52, only the upper end of which
is shown. This cylinder block 52 defines a cylinder bore 53 in
which a piston 54 is supported for reciprocation. The axis of the
cylinder bore is indicated as "C.B". The piston 54 has a skirt
portion 55 that faces the cylinder bore 53 and which terminates at
its upper end in a head portion 56. The head portion 56 has a
plurality of ring grooves 56 and 57 in which piston rings 58 and 59
are received for providing compression and oil sealing
purposes.
The piston 54 further has a pair of bosses 61 on the inner portion
thereof that have piston pin receiving openings 62 to receive a
piston pin for connection to the small end of a connecting rod, the
big end of which is journalled on the crankshaft. None of these
latter elements are illustrated in the figure for the reasons
aforenoted.
The cylinder block 52 is also formed with a cooling jacket 63 which
surrounds its cylinder bores 53 and through which coolant is
circulated in a suitable manner.
Affixed to the cylinder block 52 in a suitable manner, which may
include integral formation, is a cylinder head member 64. The
cylinder member 64 has a first surface 65 which is in sealing
engagement with the cylinder block 52 around its cylinder bores 53.
A recessed surface area is formed therein over the piston 54 having
a configuration, which will be described shortly for completing the
formation of the combustion chamber S.
On one side of a diametrical plane passing through the axis C.B. of
the cylinder bore 53 there are formed a pair of intake passages 66
which terminate at intake ports 67 that lie in a first angularly
inclined surface of the combustion chamber recess formed therein.
Intake valves 68 cooperate with valve seats formed at the intake
ports 67 so as to control the admission of an intake air charge
into the combustion chamber S. These intake valves 68 have their
stem portions slidably supported in valve guides 69 formed in the
cylinder head 64. These intake valves 68 are opened by any suitable
form of valve actuating mechanisms and are closed by suitable
return springs, the construction of which valve operation may be of
any suitable type.
On the opposite side of the aforementioned diametrical plane, there
are formed a pair of exhaust passages 71 which terminate in exhaust
ports 72. These exhaust ports 72 lie in a second inclined surface
of the cylinder head combustion chamber surfaces and these two
cylinder head inclined surfaces generally merge along the
diametrical plane that contains the cylinder bore axis C.B.
The flow through the valve seats formed at the exhaust ports is
controlled by exhaust valves 73 which, like the intake valves, are
slidably supported in valve guides 74 fixed in the cylinder head
64. As with the intake valve 68, the exhaust valve 73 may be
operated any suitable type of operating mechanism.
The angle between the reciprocal axes of the intake valves 68 and
the exhaust valves 73 may be kept fairly shallow so that the
compression ratio can be maintained high. Also, this permits the
formation of a more compact cylinder head assembly and leaves a
greater amount of room for a fuel injector 75 that is mounted in an
injector pocket 76 formed on the intake side of the cylinder head
64. Fuel is supplied to the fuel injector 75 through a fuel rail 77
in a well known manner.
Spark plugs 78 are mounted in the cylinder head 64 generally on the
cylinder bore axis C.B. which is substantially the center of the
combustion chamber S.
A cooling jacket arrangement indicated by the reference numeral 79
is formed in the cylinder head 64 and communicates with the
cylinder block cooling jacket 63 in an appropriate manner for
cooling the cylinder head 64.
The fuel injector 75 has its spray axis directly downwardly toward
the piston head 56 in a manner, which will now be described in more
detail by particular reference to FIGS. 4 and 5 in addition to FIG.
3. As seen in these figures, the piston head 56 is formed by a pair
of angularly related portions 81 and 82 formed on the intake and
exhaust sides thereof, respectively. It will be seen that the
inclined portions 81 and 82 do not actually intersect each other,
but rather intersect a generally planar surface 83 formed centrally
of the piston head 56. Partially because the diameter of the
exhaust ports 72 is smaller than that of the intake ports 67, the
surface 83 is somewhat offset toward the exhaust side so that the
inclined surface 81 has a longer range than the exhaust side
surface 82.
The surfaces 81 and 82 are disposed to be substantially parallel to
the surfaces in which the intake ports 67 and exhaust ports 72 of
the cylinder head 64 are formed. Both of these inclined surfaces 81
and 82 are bounded by curved cutouts 84 and 85 to clear the intake
and exhaust valves 68 and 73, respectively. the curved portions 84
on the intake side are joined by a tangential wall 86.
On the other hand, on the exhaust side the curved portions 84
extend inwardly toward the flat surface 83 so as to assist in
increasing the compression ratio. No such corresponding portion is
formed on the intake side as seen by the shaded area in FIG. 4.
This leaves a squish area 87 on the exhaust side periphery and a
somewhat smaller squish area 88 on the intake side periphery of the
piston head 56.
The central part of the flattened area 83 at the top of the piston
head is formed with a recess 89 so as to provide clearance for the
spark plug 78 and specifically the gap thereof at top dead
center.
On the intake side and specifically in the area below the tip of
the fuel injector 75 the squish area 88 is provided with a
clearance groove 91 of somewhat short radial extent that intersects
a further fan-shape relieved area 92 so as to permit the fuel
sprayed from the injector 75 to impact on the piston head surface
portion 81 and spread while confining it from impinging on the
outer periphery of the piston head 56. The angle .crclbar. of this
fan-shaped area 92 is preferably in the range of 120.degree. but
this angle will depend upon the injection spray pattern of the
injector nozzle.
As may be best seen in FIG. 3, the fuel is sprayed from the
injector 75 and flows downwardly toward the piston inclined surface
81. This surface 81 will direct the sprayed fuel in the manner
shown in the shaded patch in FIG. 3 toward the head of the exhaust
valves 74 so as to improve vaporization. This prevents the
generation of smoke.
FIG. 1 shows the condition at top dead center when running at an
engine speed of 7200 rpm. Fuel is injected from the end of the
exhaust stroke to the later half of the intake stroke at crank
angles ranging from 380.degree. before top dead center to
250.degree. before top dead center at this engine speed. In
addition to improving the fuel vaporization, the fuel impingement
on the exhaust valves 73 aids in their cooling and also the intake
side of the piston head 56 is cooled by this fuel impingement so as
to increase the knocking limit.
Thus, from the foregoing description it should be readily apparent
that the described embodiment of the invention permits the use of
high compression ratios with direct injected engines and also
avoids the likelihood of smoke generation as well as improving
temperature control within the combustion chamber. Of course, the
foregoing description is that of a preferred embodiment of the
invention and various changes and modifications may be made without
departing from the spirit and scope of the invention, as defined by
the appended claims.
* * * * *